1. Field of the Invention
This invention relates to a clutch means and more particularly to a roller type locking clutch especially adapted for use in a four-wheel drive vehicle or the like.
2. Description of the Prior Art
During operation of a four-wheel drive vehicle or the like, it is desirable that the front wheels of the vehicle can disconnect with respect to respective driving members such as the front axle shafts or the like of the vehicle. In this manner, the front wheels are in a free-run or free-wheeling relationship with the driving member. At other times, it becomes desirable to automatically lock the front wheels to the respective driving members whenever the driving members are rotated. Typical automatic clutch means which lock the front wheels to respective driving members have an inherent problem in that, as the driving member rotates slower than the front wheels, as occurs when the throttle of the vehicle is suddenly released or the vehicle descends a downgrade, the clutch means allow the front wheels to free-run with respect to the driving members. The present invention overcomes this problem by automatically maintaining the front wheels and the respective driving members in a locked relationship whenever the driving members are rotating. In this manner the normal vehicle engine compression is used to brake the speed of the vehicle through front and rear wheels as the vehicle throttle is released or as the vehicle descends a downgrade.
Petrak U.S. Pat. No. 3,217,847, discloses an automatic clutch with a locking means but differs from the present invention in that in the Petrak clutch a clutch ring is axially displaced into a splined engagement with a driven member. Goble U.S. Pat. No. 3,656,598, discloses a clutch which is somewhat similar to the Petrak clutch and differs from the present invention in that it also uses a sliding clutch ring to lock the driving and driven members. Reed U.S. Pat. No. 3,414,096, discloses an automatic and manual means for a hub clutch, but differs from the present invention in that it requires a manually operated mechanism to provide engine compression braking.
As will be discussed more fully below, the present invention provides a means to automatically lock a driving member to a driven member for any relatively unequal rotation of the driven member. As the driven member overruns the driving member, as occurs when the throttle of the vehicle is released, means within the clutch automatically maintain a locked engagement between the driving and driven members, thereby allowing the engine compression to brake the forward speed of the vehicle through both front and rear wheels.